Wirelessly powered unmanned aerial vehicles and tracks for providing wireless power

ABSTRACT

Example wirelessly powered unmanned aerial vehicles and tracks for providing wireless power are described herein. An example apparatus includes a track section having a transmitter coil to generate an alternating magnetic field and an unmanned aerial vehicle having a receiver coil. The alternating magnetic field induces an alternating current in the receiver coil when the unmanned aerial vehicle is disposed in the alternating magnetic field.

RELATED APPLICATION

This patent arises from a continuation of U.S. application Ser. No.15/406,156, titled “Wirelessly Powered Unmanned Aerial Vehicles andTracks for Providing Wireless Power,” filed Jan. 13, 2017, which ishereby incorporated by this reference in its entirety.

FIELD OF THE DISCLOSURE

This disclosure relates generally to unmanned aerial vehicles and, moreparticularly, to wirelessly powered unmanned aerial vehicles and tracksfor providing wireless power.

BACKGROUND

In recent years, unmanned aerial vehicles (UAVs), which are sometimesreferred to as “drones,” have become more readily available. In fact,sporting events such as drone racing have been extremely popular. Racerscontrol their respective drones and fly them along a race track. In someinstances, racers wear virtual reality headsets that display an imagefrom their corresponding drone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional unmanned aerial vehicle (UAV) and aconventional race track for UAVs.

FIG. 2 illustrates an example UAV and an example track to providewireless power to the example UAV constructed in accordance with theteachings of this disclosure.

FIG. 3A illustrates an example horizontal track section of the exampletrack of FIG. 2 having an example transmitter coil to provide wirelesspower to the example UAV.

FIG. 3B is a block diagram representing an example implementation of theexample UAV of FIG. 2.

FIG. 4 illustrates an example vertical track section of the exampletrack of FIG. 2 having an example transmitter coil to provide wirelesspower to the example UAV.

FIG. 5 illustrates an example circuit representing the inductivecoupling between the example UAV and the example track of FIG. 2.

FIG. 6A illustrates an example birdcage transmitter coil that may beimplemented in the example horizontal track section of FIG. 3A, and FIG.6B illustrates the corresponding magnetic field generated by the examplebirdcage transmitter coil of FIG. 6A.

FIG. 7A illustrates an example spiral transmitter coil that may beimplemented in the example vertical track section of FIG. 4, and FIG. 7Billustrates the corresponding magnetic field generated by the examplespiral transmitter coil of FIG. 7A.

FIG. 8 is a top view of an example UAV having an example receiver coildisposed around the diameters of example rotors of the example UAV forreceiving wireless power.

FIG. 9 is a top view an example UAV having an example receiver coildisposed around example motors and inside the diameters of examplerotors of the example UAV for receiving wireless power.

FIG. 10 illustrates an example UAV having an example 3D form receivercoil capable of receiving wireless power in more than one direction.

FIG. 11A illustrates an example UAV having an example receiver coil in afirst orientation and which can be tilted to receive wireless power inmore than one direction.

FIG. 11B illustrates the example UAV of FIG. 11A with the examplereceiver coil in a second orientation.

FIG. 12 is a flowchart representative of example method, that may beimplemented at least in part by machine readable instructions, asimplemented by the example UAV of FIGS. 11A and 11B and, at least inpart, by the example UAVs of FIGS. 2, 8, 9 and 10.

FIG. 13 is a block diagram of an example processor system structured toexecute example machine readable instructions represented at least inpart by FIG. 12 to implement the example UAVs of FIGS. 2 and 8-11B.

Certain examples are shown in the above-identified figures and describedin detail below. In describing these examples, like or identicalreference numbers are used to identify the same or similar elements. Thefigures are not necessarily to scale and certain features and certainviews of the figures may be shown exaggerated in scale or in schematicfor clarity and/or conciseness. Additionally, several examples have beendescribed throughout this specification. Any features from any examplemay be included with, a replacement for, or otherwise combined withother features from other examples.

DETAILED DESCRIPTION

With the rise in use of unmanned aerial vehicles (UAVs) (known as“drones”), sporting activities using drones, such as drone racing or dogfighting, have gained tremendous popularity. For example, in recentyears, a major television network has begun backing drone racing withsome races having prices over of one million dollars. Some drone races,known as first person view (FPV) drone racing, provide a virtual realityexperience. A driver or racer of a drone wears a headset with a screen(e.g., a virtual reality headset) that displays a first person view ofthe flying drone. The drone is equipped with a camera that transmits thevideo feed to the racer's headset, and the racer uses a remote controlto control the drone and fly/maneuver the drone along the race course.

FIG. 1 shows a conventional race course or race track 100 used for UAVracing. The race track 100 includes horizontal track sections (e.g.,planar track section or portion), one of which is shown at referencenumeral 102, vertical track sections 104, one of which is shown atreference number 104, and plurality of gates 106. A conventional UAV 108is illustrated in the callout in FIG. 1. A driver (e.g., racer)communicates with the UAV 108 via a wireless controller. The drivercontrols the UAV 108 to fly over and along the horizontal and verticaltrack sections 102, 104. In particular, the horizontal track sections102 define the horizontal boundaries of the race track 100. The driverflies the UAV 108 over the horizontal track sections 102 and over thevertical track sections 104. Additionally, in some races, the UAV 108 isrequired to fly through the gates 106, which are spaced apart at thedifferent sections of the race track 100, and which prevent the UAV 108from diverting too far from the race track 100 (e.g., the gates 106limit movement in the vertical direction). In some instances, the UAV108 is equipped with a camera that records an image in front of the UAV108 and transmits the image to a headset or display screen for thedriver. In other instances, the driver may stand near the race track andwatch the UAV. Races may be performed with one UAV at a time (e.g., atime trial) or multiple UAVs at the same time.

In FIG. 1, the UAV 108 includes four rotors 110 that generate lift topropel the UAV 108 and keep the UAV 108 suspended in the air. The rotors110 are driven by electric motors 112 (e.g., direct current (DC)motors). The UAV 108 also includes a battery 114 (or battery pack) topower the electric motors 112 and other electronics on the UAV 108. Whenthe charge in the battery 114 is depleted, the driver must perform a pitstop to switch out the battery 114 of the UAV 108. For instance, mostracing drones (such as the UAV 108) can only fly for about 10-15 minuteswith a charged battery. Thus, the battery 114 severely limits the flyingtime of the UAV 108. Also, as can been seen in FIG. 1, the battery 114is relatively large and also adds significant weight to the UAV 108. Inmost instances, the battery 114 accounts for more than a third of theoverall weight of the UAV 108. Thus, the volume and weight of thebattery 114 severely limit the speed and acceleration of the UAV 108. Inparticular, a racing drone (such as the UAV 108) can only fly about 60miles per hour (mph).

Disclosed herein are example wirelessly powered UAVs and tracks thatprovide wireless power to UAVs and, thus, eliminate the need for abattery or significantly reduce the size of the battery needed in theUAVs. As a result, an example UAV can fly for an unlimited time withouthaving to change the battery. Further, with no battery or a relativelysmaller battery, the weight of the example UAV is significantly lessthan known UAVs. As such, example UAVs can achieve greater speeds (e.g.,greater than 60 mph) and accelerations than known UAVs, which greatlyimproves the drone racing experience.

Example tracks disclosed herein include one or more track sections thatprovide wireless power through inductive coupling. In general, ininductive coupling, power is transferred between coils of wire by amagnetic field. An alternating current (AC) through a transmitter coilcreates an alternating or oscillating magnetic field in accordance withAmpere's Law. The magnetic field passes through a receiver coil where itinduces an alternating electromotive force (EMF) or voltage, therebygenerating an AC signal in the receiver coil that may be used to drive aload (e.g., an example UAV). In other words, the two coils areinductively coupled when they are configured such that a change incurrent through one of the coils induces a voltage across through thecoil via electromagnetic induction. As such, power is transmittedwithout the use of discrete human-made conductors (e.g., wires).

In some examples disclosed herein, an example track includes one or moretrack sections having a transmitter coil. The transmitter coil defines apassageway (or space) through which one or more UAVs can fly. Thetransmitter coil generates a time-varying magnetic field in thepassageway. Example UAVs disclosed herein carry a receiver coil. When anexample UAV is disposed inside the passageway (i.e., when the receivercoil is positioned in the alternating magnetic field), an oscillatingvoltage or current is induced in the receiver coil. The induced ACsignal may be used to power one or more of the component(s) (e.g., theelectric motor(s), the camera, etc.) of the UAV or may be rectified to adirect current (DC) signal and used to power the one or morecomponent(s) of the UAV. In some examples, the DC signal is used tocharge a battery or battery pack, which may be used at a later time topower the component(s). The example transmitter coils disclosed hereinadvantageously create a substantially uniform field in thethree-dimensional (3D) volume defined by the transmitter coil. As such,an example UAV can receive constant and continuous power anywhere insidethe passageway. For example, the UAV can travel up or down and/orside-to-side within the transmitter coil and still receive the samerelative power. Further, the example transmitters coils disclosed hereincan provide wireless power to multiple UAVs simultaneously.

FIG. 2 illustrates an example track 200 that provides wireless power toone or more UAVs. An example wirelessly powered UAV 202 is illustratedin the callout in FIG. 2. In the illustrated example, the track 200includes a plurality of horizontal track sections, one of which is shownat reference numeral 204, and a plurality of vertical track sections,one of which is shown at reference numeral 206. In the illustratedexample, the horizontal track sections 204 and the vertical tracksections 206 are coupled in series to form a passageway (e.g., a tube)through which one or more UAVs (e.g., the UAV 202) can fly. The UAV 202flies through the horizontal track sections 204 in a substantiallyhorizontal direction and through the vertical track sections 206 in asubstantially vertical direction (e.g., up and down). In other examples,the track 200 may include more or fewer horizontal or vertical tracksections 204, 206 and/or may be arranged in other layouts orconfigurations.

In the illustrated example, the UAV 202 includes a body 207 and fourrotors 208 (e.g., propellers). UAVs with four rotors are commonlyreferred to as a quad-copter. In some examples, the body 207 containsthe electronics and other various component(s) of the UAV 202. Therotors 208 generate lift to propel the UAV 202 and levitated the UAV 202in the air. In the illustrated example, the rotors 208 are driven byelectric motors 210 (e.g., a brushless DC motor). In other examples, theUAV 202 may have more (e.g., six, eight, etc.) or fewer (e.g., three,one) rotors and, thus, more or fewer electric motors. Furthermore, otherUAV body and/or rotor configurations may additionally or alternativelybe used such as, for example, a helicopter configuration (e.g., onehorizontal rotor and one vertical rotor), a fixed wing configuration,etc.

While disposed in the passageway formed by the track 200, the UAV 202receives wireless power from the track 200. The track 200 creates anoscillating or alternating magnetic field in the passageway, asdisclosed in further detail herein. In the illustrated example, the UAV202 includes a receiver coil 212 that receives wireless power from thetrack 200. In particular, when the receiver coil 212 is exposed to thealternating magnetic field in the passageway, a voltage is induced inthe receiver coil 212, which can be used to power the UAV 202. Thereceiver coil 212 may include one or more turns of wire. In someexamples, only a few turns (e.g., three turns) are implemented. However,in other examples, the receiver coil 212 may include hundreds or eventhousands of turns. In the illustrated example, the receiver coil 212 isring-shaped. In the illustrated example, the receiver coil 212 isdisposed outside a diameter of the rotors 208. In other words, adiameter of the receiver coil 212 is larger than a width or span of therotors 208. In some examples, using a receiver coil that encompasses thewhole UAV (or a relatively large section of the UAV) results in a higher(e.g., a maximum) Q factor and coupling between the receiver coil 212and the transmitter coil (discussed in further detail herein). In otherexamples, the receiver coil 212 may be disposed in another locationand/or shaped differently.

In the illustrated example, the UAV 202 has a battery 214, which may beused to store electrical power. In the illustrated example, the battery214 is relatively small compared to batteries of known UAVs. In someexamples, the current induced in the receiver coil 212 is used to chargethe battery 214. However, in other examples, the UAV 202 may not have abattery. Instead, the current generated in the receiver coil 212 can beused directly to power the various component(s) of the UAV 202. Whilethe example UAV 202 includes the receiver coil 212, the overall weightof the UAV 202 is still significantly less than the weight of known UAVsbecause of the elimination or reduction in size and weight of thebattery 214. Thus, the example UAV 202 is capable of achieving higherspeeds and accelerations than known UAVs. Further, the example UAV 202is able to fly significantly longer (e.g., for an unlimited amount oftime) than known UAVs (which need to stop every 10-15 minutes to switchout batteries).

While in the illustrated example of FIG. 2 the horizontal and verticaltrack sections 204, 206 form a substantially continuous passageway, inother examples there may be breaks or gaps between sections of the track200. As such, wireless powering may only occur in certain sections orareas of the track 200. For example, the UAV 202 may receive wirelesspower from certain sections of the track 200 and which may be used tocharge the battery 214. The battery 214 can then be used to power theUAV 202 in other sections of the track 200 that do not provide wirelesspower. Further, one or more sections may be used to form a space tosupport wireless powered dog fighting and/or sections where a UAV canwirelessly charge a battery and then resume dog fighting.

FIG. 3A illustrates the example UAV 202 flying through one of theexample horizontal track sections 204. In the illustrated example, thehorizontal track section 204 defines a passageway 300 through which theUAV 202 can fly. When the UAV 202 is disposed within the passageway 300,the UAV 202 receives wireless power from the horizontal track section204. As illustrated in FIG. 3A, the receiver coil 212 is disposed in asubstantially horizontal orientation. In general, magnetic flux througha receiver coil is the highest (e.g., maximum) when the receiver coil isperpendicular to the magnetic flux. Thus, to provide wireless power tothe UAV 202, the horizontal track section 204 generates an alternatingmagnetic field (represented by the vertical dotted arrows) in thevertical (up and down) direction in the passageway 300, which isperpendicular to the receiver coil 212. As such, the alternatingmagnetic field passes through the receiver coil 212 and induces acurrent.

To create the alternating magnetic field in the passageway 300, theexample horizontal track section 204 includes a transmitter coil 302. Inthe illustrated example, the transmitter coil 302 defines the passageway300. The transmitter coil 302 is constructed of one or more conductingelements (e.g., a copper wire). In some examples, the conductingelement(s) are insulated or embedded in an insulating material (e.g.,rubber, plastic, etc.), which provides rigidity to the transmitter coil302 and/or defines the horizontal track section 204. In other examples,the horizontal track section 204 is formed by a frame or other rigidmaterial and the transmitter coil 302 is embedded into the materialand/or otherwise coupled to the material around the passageway 300.

In the illustrated example of FIG. 3A, the transmitter coil 302 isconfigured to generate an alternating current in a directionperpendicular to a central axis 304 of the passageway 300 defined by thetransmitter coil 302. The transmitter coil 302 includes a first end ring306 and a second end ring 308 spaced apart from each other along thecentral axis 304. Further, the transmitter coil 302 includes a pluralityof rungs 310 (sometimes referred to as legs) between the first andsecond end rings 306, 308. This type of configuration is sometimesreferred to as a birdcage coil. In the illustrated example, the rungs310 are oriented substantially parallel to each other and spacedequidistant from each other around the first and second end rings 306,308. In the illustrated example, capacitors 312 are disposed in along(e.g., in circuit with, integrated in) each of the rungs 310. In otherexamples, the capacitors 312 may be disposed along the first and secondend rings 306, 308 between each of the rungs 310. In other examples, thecapacitors 312 may be arranged in other configurations and/or additionalcapacitors may be utilized depending on the desired frequencycharacteristic.

To generate an electrical signal in the transmitter coil 302 and createan alternating magnetic field the passageway 300, the horizontal tracksection 204 includes a transmitter circuit 314. The transmitter circuit314 includes an oscillator 316 (e.g., an AC generator) and a powersource 318. The power source 318 may include a stored energy source(e.g., a battery or battery pack) and/or may utilize power directly froma power line (e.g., from the power grid). The oscillator 316 uses powerfrom the power source 318 and creates an AC signal at resonant frequencyin the transmitter coil 302. The configuration of the first and secondend rings 306, 308, the rungs 310 and the capacitors 312 createssinusoidal currents in each of the rungs 310 that are sequentially phaseshifted around the periphery of the first and second end rings 306, 308.For example, if there are N rungs, the phase shift between the currentsin neighboring runs is 360°/N. The AC creates an alternating magneticfield in a direction that is perpendicular to the central axis 304within the spaced (3D volume) defined by the transmitter coil 302, i.e.,the passageway 300. Thus, if the horizontal track section 204 (includingthe transmitter coil 302) is orientated substantially horizontal, themagnetic field is in the vertical direction. When the UAV 202 isdisposed inside the passageway 300, the alternating magnetic fieldinduces an alternating voltage in the receiver coil 212, which isoriented substantially perpendicular to the alternating magnetic field.In the illustrated example, the transmitter coil 302 generates asubstantially constant or uniform magnetic field throughout thepassageway 300. This uniform field is advantageous because the UAV 202may receive power while flying at different elevations and/or lateralpositions in the passageway 300. In other words, the UAV 202 can receivepower while flying from one end to the other end of the horizontal tracksection 204.

In some examples, the alternating magnetic field operates a frequency of6.78 mega-hertz (MHz). In other examples, the transmitter coil 302 maybe tuned to produce an alternating magnetic field at a higher or lowerfrequency (e.g., 85 kilo-hertz (kHz) or 13.56 MHz). The first end ring306 and the second end ring 308 may be coupled to or otherwise disposedadjacent the openings of upstream or downstream track sections to form asubstantially continuous passageway through which the UAV 202 can flythrough. In other words, a series of the horizontal track sections 204may be arranged to form a substantially continuous passageway that canprovide wireless power to the UAV 202.

While in the illustrated example the horizontal track section 204 issubstantially linear or straight, in other examples the horizontal tracksection 204 may be curved. For example, the rungs 310 on one side may belonger than the rungs 310 on the other side, and the first and secondend rings 306, 308 may not be parallel to each other. Such aconfiguration provides a curved passageway through which the UAV 202 canfly and still provides a substantially constant and uniform magneticfield in the passageway.

FIG. 3B illustrates a block diagram representing an exampleimplementation of the example UAV 202. The block diagram of FIG. 3B mayalso implement other UAVs, such as the UAVs 800, 900, 1000, 1100disclosed in connection with FIGS. 8-11B below. In the illustratedexample, the UAV 202 includes an example electronics power controller320 (e.g., a power circuit) in circuit with the receiver coil 212. Theelectronics power controller 320 supplies and/or regulates the power(based on the current induced in the receiver coil 212) to the variouscomponent(s) of the UAV 202 (e.g., the electric motors 210). In someexamples, the electronics power controller 320 includes a rectifier 322(e.g., an AC to DC converter) in circuit with the receiver coil 212. Therectifier 322 converts the AC signal induced in the receiver coil 212into a DC signal that can be used to power the various components of theUAV 202. In other examples, no rectifier may be provided. Instead, oneor more of the component(s) of the UAV 202 may operate on AC power(e.g., the electric motors 210 may be AC motors). In some examples, theelectronics power controller 320 includes an amplifier and/or otherelectronics to condition the alternating current induced in the receivercoil 212 to be used by the various component(s) of the UAV 202. Theelectronics power controller 320 may supply the power to the battery 214and/or supply the power directly to the various components of the UAV202. Thus, in some examples, the power (e.g., a DC signal) is used tocharge the battery 214, which can then be used at a later time to powerthe UAV 202. As mentioned above, while in the illustrated example theUAV 202 includes the battery 214, in other examples no battery may beprovided, and the UAV 202 may instead directly use the power received bythe receiver coil 212.

In the illustrated example of FIG. 3B, the UAV 202 includes acommunication system 324, which communicates with one or more externalsystems such as the remote controller used by the driver. Thecommunication system 324 may include a transmitter and/or receiver(e.g., transceiver) to communicate with the driver and/or anothersystem. In some examples, the UAV 202 includes a camera 326 that recordsan image of the environment in front of the UAV 202. In some examples,the recorded image is transmitted (via a transmitter of thecommunication system 324) to the driver to provide a live or near-liveview (e.g., first person view) of the flying UAV 202. In some instances,the image is displayed on a virtual reality headset or other displayscreen. In the illustrated example, the example UAV 202 also includesthe electric motors 210, which operate the rotors 208 to provide liftand/or directional control for the UAV 202. The example electric motors210 are DC electric motors. In other examples, other types of motors(e.g., an AC motor) may be implemented. The power received by thereceiver coil 212 is used to power the communication system 324, powerthe camera 326, power the electric motors 210, charge the battery 214and/or provide power to any other electrical component or system (e.g.,a guidance system, a light, etc.).

While only one UAV is depicted in FIG. 3A, the horizontal track section204 may accommodate more than one UAV and provide equal and constantpower to all of the UAVs in the passageway 300. Below is an examplecalculation illustrating an amount of power needed by the horizontaltrack section 204 to provide constant power to multiple UAVs. Assume thepassageway 300 is 1.5 meters (m) in diameter (e.g., the first and secondend rings 306, 308 are 1.5 m in diameter). Also assume the capacitors312 have a capacitance of 9.5 pico-farad (pF). With this configuration,the transmitter coil 302 can achieve a series resonance at 6.78 Mhz.Also assume the receiver coil 212 on the UAV 202 is a 5-turn solenoidcoil with a radius of 12.5 centimeters (cm), which allows the passageway300 to accommodate a total of six UAVs side-by-side (e.g., each receivercoil is 25 cm in diameter so six receiver coils can fit within the 1.5 mpassageway 300). In this example, the mutual coupling between thetransmitter coil 302 and the receiver coil 212 is 4.14 ohms. Thereceiver coil 212 has an area A=πr²=0.049 m². Suppose the rotors 208occupy the majority area inside the receiver coil 212. In a relativelyshort time duration Δt, a total volume of air, represented by A×v×Δt,where v is velocity, is pushed by the rotors 208. Thus, the totalkinetic energy provided by the UAV 202 gained by the air in duration Δtis given by Equation 1 below.P min×Δt=½×v ³ ×A×ρ×Δt  Equation 1

In Equation 1, p is the mass density of air and P min is the minimumpower need for the UAV 202 to hover. The total momentum p gained by theair in time duration Δt is given by Equation 2 below.p=v ² ×A×ρ×Δt  Equation 2

The counterforce provided by the air to the UAV 202 is given by Equation3 below.F×Δt=p  Equation 3

In Equation 3, F is the force balancing the weight of the UAV 202. Inparticular, F=mg, where m is the mass of the UAV 202 and g is the forceof gravity. Then, the minimum power P_(min) can be found using Equation4 below, which is a combination of Equations 1, 2 and 3.

$\begin{matrix}{P_{\min} = {\frac{1}{\sqrt[4]{\rho\; A}}( {2{mg}} )^{3\text{/}2}}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

Assume, for example, the mass density ρ is 1.2 kg/m³, the mass m of theUAV 202 is 500 grams (g), and gravity g is 9.8 Netwons/kilogram (N/kg),then the minimum power P_(min) required for the UAV 202 to hover is 31.6Watts (W). Assuming the resistance of the receiver coil 212 is about 0.9ohm, then to deliver 31.6 W at 95% receiver coil efficiency, thereceiver voltage needed is about 24V, which corresponds to a transmittercoil input current of 5.8 A. Thus, the field that is required to deliverthis power is about 2.4 ampere per meter (A/m) inside the transmittercoil 302. Thus, the total power needed to generate such an alternatingmagnetic field is not only practical, but relatively small compared toother power demands of other wireless power devices.

FIG. 4 shows the example UAV 202 flying through one of the examplevertical track sections 206. Similar to the horizontal track section204, the vertical track section 206 defines a passageway 400 throughwhich the UAV 202 can fly. When the UAV 202 is disposed within thepassageway 400, the UAV 202 receives wireless power from the verticaltrack section 206. In particular, the vertical track section 206generates an alternating magnetic field (represented by the verticaldotted arrows) in the vertical (up and down) direction in the passageway400, which is perpendicular to the receiver coil 212. Thus, as the UAV202 travels up or down in the passageway 400, the alternating magneticfield passes through the receiver coil 212 and induces a current.

To create the alternating magnetic field in the passageway 400, theexample vertical track section 206 includes a transmitter coil 402. Inthe illustrated example, the transmitter coil 402 is in the shape of aspiral (having a plurality of turns) that defines the passageway 400.The transmitter coil 402 is constructed of one or more conductingelements (e.g., a copper wire). In some examples, the conductingelement(s) are insulated or embedded in an insulating material (e.g.,rubber, plastic, etc.), which provides rigidity to the transmitter coil402 and/or defines the vertical track section 206. In other examples,the vertical track section 206 is formed by a frame or other rigidmaterial and the transmitter coil 402 is embedded into the materialand/or otherwise coupled to the material around the passageway 400.

Similar to the horizontal track section 204 in FIG. 3A, the verticaltrack section 206 of FIG. 4 includes a transmitter circuit 404 togenerate an alternating current in the transmitter coil 402, therebygenerating an alternating magnetic field in the passageway 400. Inparticular, the transmitter circuit 404 includes an oscillator 406 and apower source 408. In some examples, the powers source 318 (FIG. 3A) usedto power the horizontal track section 204 is the same as the powersource 408 used to power the vertical track section 206. In theillustrated example, the oscillator 406 generates an AC signal in thetransmitter coil 402, which generates an alternating magnetic field in adirection aligned with a central axis 410 of the passageway 400 definedby the transmitter coil 402. As such, when the UAV 202 moves verticallyup or down through the passageway 400, the receiver coil 212 is orientedperpendicular to the alternating magnetic field. The alternatingmagnetic field passes through the receiver coil 212, thereby inducing analternating current in the receiver coil. While in the illustratedexample the transmitter coil 402 is substantially linear or straight, inother examples the passageway 400 may be curved. In such an example, thetransmitter coil 402 still generates an alternating magnetic field in adirection substantially parallel to a central axis through thetransmitter coil 402. In other examples, other types of coils may beimplemented as the transmitter coil 402 to generate an alternatingmagnetic field such as a Maxwell coil or a Helmholtz coil.

Thus, as can been in FIGS. 2-4, the UAV 202 can receive power from thetrack 200 while flying through the horizontal and vertical tracksections 204, 206, which generate an alternating magnetic field in thevertical direction and, thus, perpendicular to the horizontalorientation of the receiver coil 212. The horizontal and vertical tracksections 204, 206 may be any length depending on the design of thetrack. In some examples, each of the horizontal and vertical tracksections 204, 206 of the track 200 may include a separate transmittercircuit (e.g., the transmitter circuit 314 (FIG. 3A), the transmittercircuit 404 (FIG. 4)). In other examples, multiple sections of the track200 may be controlled by a common transmitter circuit, which generatesan alternating current in each of the sections and/or uses the samepower source.

In some examples, instead of using the transmitter coil 302 (FIG. 3A)having the birdcage configuration for the horizontal track section 204,the horizontal track section 204 may include a spiral transmitter coil,similar to the transmitter coil 402 of FIG. 4, which creates analternating magnetic field in a direction parallel to a central axis ofthe transmitter coil. In such an example, the receiver coil 212 of theUAV 202 may be oriented in a substantially vertical direction, such thatthe alternating magnetic field (in the horizontal direction) istransmitted through the receiver coil 212. Likewise, instead of usingthe transmitter coil 402 having a spiral shape for the vertical tracksection 206, the vertical track section 206 may include a birdcage coil,similar to the transmitter coil 302 of FIG. 3A, which creates analternating magnetic field in a direction perpendicular to a centralaxis of the transmitter coil. Thus, with the receiver coil 212 orientedsubstantially vertical, the horizontal alternating magnetic field passesthrough the receiver coil 212.

FIG. 5 depicts a circuit representation of the power transfer betweenthe track 200 and one or more UAVs (e.g., the UAV 202). In particular,FIG. 5 illustrates a transmitter circuit 500 representing the powertransfer between the transmitter coil 302 of one of the horizontal tracksections 204 and one or more UAVs. However, the circuit representationmay also be applied to other ones of the transmitter coils implementedin the track 200 of FIG. 2, such as the transmitter coil 402 of FIG. 4.

In the illustrated example of FIG. 5, the transmitter coil 302(represented by coil (L₁)) is series tuned to resonance at operatingfrequency ω (e.g., 6.78 MHz). For example, the transmitter circuit 314(e.g., via the oscillator 316 (FIG. 3A)) generates an AC signal in thetransmitter coil 302. The UAV 202 includes the receiver coil 212(represented by coil L₂). For example, the series resonance in thetransmitter circuit 500 and the UAV 202 are given using Equations 5 and6 below.

$\begin{matrix}{{{j\;\omega\; L_{1}} + \frac{1}{j\;\omega\; C_{1}}} = 0} & {{Equation}\mspace{14mu} 5} \\{{{j\;\omega\; L_{2}} + \frac{1}{j\;\omega\; C_{2}}} = 0} & {{Equation}\mspace{14mu} 6}\end{matrix}$

In Equation 5, C₁ represents the capacitor in the transmitter circuit500, and in Equation 6, C₂ represents the capacitor in the circuitrepresenting the UAV 202. As shown in Equation 5, the impedance of thetransmitter coil 302 (represented by jωL₁) is equal or balanced with thenegative impedance of the capacitor C₁ (represented by 1/jωC₁) in thetransmitter circuit 500. Likewise, as shown in Equation 6, the impedanceof the receiver 212 (represented by jωL₂) is equal or balanced with thenegative impedance of the capacitor C₂ (represented by 1/jωC₂) in thecircuit representing the UAV 202.

When the UAV 202 is disposed in the alternating magnetic field generatedby the transmitter coil 302, an inductive coupling is establishedbetween the transmitter coil 302 (L₁) and the receiver coil 212 (L₂)(represented by mutual impedance Z₂₁), and the equivalent load R_(L0) ofthe UAV 202 (e.g., the motors 210, the camera 326, etc.) is reflected tothe transmitter circuit 500 as a series resistance Z₂₁ ²/R_(L0). Thisrelationship ensures that as the power demand of the UAV 202 increases(e.g., when the UAV 202 accelerates or rises vertically), the equivalentload R_(L0) reduces and, thus, the reflected impedance to thetransmitter circuit 500 would increase. As long as the transmittercircuit 500 is able to provide a constant AC (represented by I_(TX)),the power (P₂) provided by the transmitter circuit 500 to the UAV 202increases. In other words, the transmitter coil 302 is able to supplyproper power to the UAV 202 as it demands, without need of a controlloop or side band communication.

In some examples, multiple UAVs may draw power from the transmitter coil302. A second UAV 502 is illustrated in FIG. 5. Similar to the UAV 202(the first UAV 202), the second UAV 502 includes a receiver coil(represented by L₂). When the receiver coil L₂ of the second UAV 502 isdisposed in the alternating magnetic field of the transmitter coil 302,the receiver coil L₂ couples to the transmitter coil 302 and its powerdemand is reflected to the transmitter circuit 500 as a seriesresistance Z₃₁ ²/R_(L1). As long as the transmitter circuit 314maintains a constant AC (I_(TX)), the second UAV 500 can receive power(P₃) from the transmitter coil 302 without impacting the power (P₂)delivered to the first UAV 202, and vice versa. Thus, multiple UAVs mayreceive power from the transmitter coil 302 without affect the powerdeliver to the other UAVs. The power (P₂) delivered to the UAV 202 andthe power (P₃) delivered to the second UAV 502 are provided by Equations7 and 8 below, respectively.

$\begin{matrix}{P_{2} = {I_{TX}^{2}\frac{Z_{21}^{2}}{R_{L}}}} & {{Equation}\mspace{14mu} 7} \\{P_{3} = {I_{TX}^{2}\frac{Z_{31}^{2}}{R_{L}}}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

Example techniques to provide constant current behavior power amplifierare disclosed in U.S. application Ser. No. 14/861,931, titled “ConstantCurrent Radio Frequency Generator for a Wireless Charging System,” andfiled Sep. 22, 2015, which is hereby incorporated by reference in itsentirety. The example techniques disclosed in the above-referencedapplication can be used to provide constant AC to the transmittercircuit 500, for example, and, thus, provide power to one or more UAVs.

FIG. 6A illustrates an example birdcage transmitter coil 600, and FIG.6B illustrates the magnetic field (in A/m) generated in and around thebirdcage transmitter coil 600 of FIG. 6A. The example birdcagetransmitter coil 600 may correspond to, for example, the exampletransmitter coil 302 (FIG. 3A), which may be implemented in one or moreof the example horizontal or vertical track sections 204, 206. Similarto the transmitter coil 302 of FIG. 3A, the example birdcage transmittercoil 600 includes a first end ring 602, a second end ring 604 and aplurality of rungs 606 between the first and second end rings 602, 604.The birdcage transmitter coil 600 defines a passageway 608 having acentral axis 610. As illustrated in FIG. 6B, the birdcage transmittercoil 600 creates a relatively uniform magnetic field in the passageway608 defined by the rungs 606 and between the first and second end rings602, 604. In particular, the magnetic field is perpendicular to thecentral axis 610 (e.g., a horizontal axis or plane) of the birdcagetransmitter coil 600. If the birdcage transmitter coil 600 is orientatedhorizontally, for example, the magnetic field in the passageway 608 isin the vertical direction. In FIG. 6B, the magnetic field lines spiralaround the first and second end rings 602, 604. However, when additionalbirdcage transmitter coils are disposed upstream and downstream (on theleft and right in FIGS. 6A and 6B) of the birdcage transmitter coil 600,the spiral field lines are eliminated and only the vertical magneticfield lines are present.

FIG. 7A illustrates an example spiral transmitter coil 700, and FIG. 7Billustrates the magnetic field generated in and around the spiraltransmitter coil 700 of FIG. 7B. The example spiral transmitter coil 700may correspond to, for example, the example transmitter coil 402 (FIG.4), which may be implemented in one or more of the example horizontal orvertical track sections 204, 206. In the illustrated example, the spiraltransmitter coil 700 defines a passageway 702 having a central axis 704.As illustrated in FIG. 7B, the spiral transmitter coil 700 creates arelatively constant magnetic field in the passageway 702, which isparallel to or aligned with the central axis 704 of the spiraltransmitter coil 700. In the illustrated example, the spiral transmittercoil 700 includes two loops or turns. However, in other examples, thespiral transmitter coil 700 may include more (e.g., three, five, ten,etc.) or fewer (e.g., one) turns. In the illustrated example, the turnsof the spiral transmitter coil 700 are separated by distance D. Further,in the illustrated example, the spiral transmitter coil 700 has a radiusR. In some examples, the radius R is 0.75 m. However, in other examples,the radius R may be larger or smaller depending on the desired size ofthe passageway through the spiral transmitter coil 700.

While in the illustrated example of FIGS. 2-4 the receiver coil 212 isdisposed around the rotors 208 of the UAV 202, in other examples thereceiver coil 212 can be shaped differently and/or disposed in otherlocations. For example, FIGS. 8 and 9 illustrate example UAVs havingdifferent receiver coil configurations and which may be used to receivepower from the track 200, similar to the UAV 202 disclosed herein. FIG.8 illustrates an example UAV 800 having a body 802, four rotors 804 anda protective frame 806 around an outer diameter the rotors 804. In otherexamples, the UAV 800 may have more (e.g., six, eight, etc.) or fewer(e.g., three, one) rotors. In the illustrated example, the UAV 800includes a receiver coil 808 that is embedded or integrated into theprotective frame 806. Thus, the receiver coil 808 is disposed outside ofa diameter of the rotors 804. In other examples, the receiver coil 808may be carried on a top or a bottom of the protective frame 806. Similarto the UAV 202 disclosed in connection with FIGS. 2-4, when the receivercoil 808 is in the presence of an alternating magnetic field, a currentis induced in the receiver coil 808, which may be used to power thevarious component(s) of the UAV 800.

FIG. 9 illustrates another example UAV 900. In the illustrated example,the UAV 900 has a body 902 and six rotors 904 operated by respectivemotors 906. In other examples, the UAV 900 may have more (e.g., eight,ten, etc.) or fewer (e.g., four, two, etc.) rotors. The example UAV 900includes a receiver coil 908. In the illustrated example, the receivercoil 908 is disposed around the motors 906 but within an outer diameterof the rotors 904. In other examples, the receiver coils 808, 908 of theUAVs 800, 900 may be disposed in other locations and/or shapeddifferently (e.g., having a larger or smaller radius).

FIGS. 10, 11A and 11B illustrate example UAVs having receiver coilscapable of capturing magnetic flux in more than one direction relativeto the UAV. The UAVs of FIGS. 10 and 11 may receive power from the track200, similar to the UAV 202 disclosed herein. FIG. 10 illustrates anexample UAV 1000 having a body 1002 and four rotors 1004. In otherexamples, the UAV 1000 may have more (e.g., six, eight, etc.) or fewer(e.g., three, one) rotors. In the illustrated example, the UAV 1000includes a 3D form receiver coil 1006. The 3D form receiver coil 1006extends in directions in all three dimensions. In particular, the 3Dform receiver coil 1006 forms loops that face different directions,which ensures capturing of the magnetic flux from different directionsas the UAV 1000 flies. In some examples, the receiver coil 1006 isformed of a single coil element (e.g., a single wire). In otherexamples, discrete or separate coil elements (e.g., multiple wires) maybe utilized. In some examples, the loops of the 3D form receiver coil1006 have different radii. For example, one radius R1 of a loop formedin the 3D form receiver coil 1006 may be larger than another radius R2of another loop formed in the 3D form receiver coil 1006. In otherexamples, all of the loops of the 3D form receiver coil 1006 may havethe same or substantially the same radius.

FIGS. 11A and 11B illustrate another example UAV 1100. The UAV 1100includes a body 1102 and four rotors 1104. In other examples, the UAV1100 may have more (e.g., six, eight, etc.) or fewer (e.g., three, one)rotors. In the illustrated example, the UAV 1100 includes a receivercoil 1106. The example UAV 1100 may correspond to the UAV 202 disclosedin FIG. 3B. To enable the receiver coil 1106 to capture magnetic fieldsin different directions, the receiver coil 1106 is movable relative tothe body 1102. For example, the receiver coil 1106 is coupled to an axle1108 that rotates (e.g., pivots) to tilt the receiver coil 1106. In theillustrated example, the axle 1108 extends through the body 1102. Theaxle 1108 may be rotated to tilt or turn the receiver coil 1106 relativeto the body 1102. For example, in the illustrated example of FIG. 11A,the receiver coil 1106 is orientated substantially horizontal and, thus,may be used in a vertical magnetic field to receive power. If themagnetic field is in the horizontal direction, the axle 1108 may berotated to turn the receiver coil 1106 to a substantially verticalorientation, as illustrated in FIG. 11B. Thus, the receiver coil 1106can capture a magnetic field in different directions.

In some examples, the receiver coil 1106 may be oriented to receive analternating magnetic field in the direction of travel. For example,assume one or more spiral transmitter coils (e.g., the transmitter coil402 and/or the spiral transmitter coil 700) are implemented in thehorizontal and vertical track sections of a race track. In such anexample, the magnetic fields are in the direction of the passageway and,thus, in the direction of travel through the transmitter coils.Therefore, in the horizontal track sections (where the magnetic field ishorizontal), the receiver coil 1106 can be titled to the verticalorientation illustrated in FIG. 11B, and in the vertical track sections(where the magnetic field is vertical), the receiver coil 1106 can betilted to the horizontal orientation illustrated in FIG. 11A. FIG. 11Ashows an example block representation of the example UAV 1100. Todetermine a direction of travel of the UAV 1100, the UAV 1100 includesone or more sensor(s) 1110. The sensor(s) 1110 may includeaccelerometers, gyroscopes, etc. Based on the direction of travel (asdetected or sensed by the sensors 1110), a controller 1112 controls amotor 1114 to rotate the axle 1108 and, thus, tilt the receiver coil1106. The controller 1112 may be implemented in the example electronicspower controller 320 of FIG. 3B. The motor 1114 may be disposed in thebody 1102 of the UAV 1100, for example.

Additionally, the receiver coil 1106 can be titled to any other anglebetween the fully vertical and horizontal orientations. Thus, thereceiver coil 1106 can be used to capture power when the magnetic fieldis not entirely vertical or horizontal. For example, if the UAV 1100 isflying through a spiral transmitter coil that is oriented 20° relativeto horizontal, the axle 1108 can be rotated to position the receivercoil 1106 at 20°, such that the receiver coil 1106 remains perpendicularto the magnetic field generated in the spiral transmitter coil.

While the example transmitter coils 302, 402, 600, 700 disclosed hereinare described in connection with a race track for UAVs, the exampletransmitter coils 302, 402, 600, 700 can be used in other applicationsto provide wireless power to one or more UAV(s). For example, a networkof UAVs may be configured (or controlled) to fly around an office orschool as transportation/delivery tools and/or personal UAV assistants.One or more transmitter coils (e.g., the transmitter coil 302, thetransmitter coil 402, etc.) can be integrated into the hallways of thebuilding to provide wireless power to the UAVs, thereby eliminating orreducing the need for batteries. As such, the weight of the UAV isdrastically reduced, which increases the overall efficiency of the UAV.Further, the UAVs can fly longer by not having to switch out batteriesand/or recharge. Thus, the UAVs can accomplish more tasks within a giventime.

Further, with the use of wireless power, another aspect can be added toUAV games and sports. For example, the magnetic field distribution ofthe different transmitters (e.g., different track sections) can bereconfigured dynamically during a race (e.g., by an organizer of therace or a player) to create a dynamic obstacle course. This would allowplayers to sabotage each other by controlling the field distribution ofcertain sections, which adds another element (and, thus, strategy) tothe race, thereby creating a more complex and interesting game.

While the example methods, apparatus/systems and articles of manufacturedisclosed herein for wirelessly powering a vehicle are described inconnection with unmanned aerial vehicles, the disclosed examples maysimilarly be implemented for manned aerial vehicles and/or othervehicles such as cars, boats, etc. For example, one or more tracksections having transmitter coils may be disposed around a track or roadfor cars. The cars may carry receiver coils, similar to the UAVsdisclosed herein and, thus, receiver wireless power as disclosed herein.

While example manners of implementing the UAVs 202, 800, 900, 1000, 1100are illustrated in FIGS. 2-5 and 8-11B, one or more of the elements,processes and/or devices illustrated in FIGS. 2-5 and 8-11B may becombined, divided, re-arranged, omitted, eliminated and/or implementedin any other way. Further, the example motor(s) 210 (which maycorrespond to any of the example motors of the example UAVs 800, 900,1000, 1110), the example receiver coil 212 (which may correspond to anyof the example receiver coils 806, 906, 1006, 1106 of the example UAVs800, 900, 1000, 1110), the example battery 214, the example electronicspower controller 320, the example rectifier 322, the examplecommunication system 324, the example camera 326, the example sensor(s)1110, the example controller 1112, the example motor 1114 and/or, moregenerally, the example UAVs 202, 800, 900, 1000, 1100 of FIGS. 2-5 and8-11B may be implemented by hardware, software, firmware and/or anycombination of hardware, software and/or firmware. Thus, for example,any of the example motor(s) 210 (which may correspond to any of theexample motors of the example UAVs 800, 900, 1000, 1110), the examplereceiver coil 212 (which may correspond to any of the example receivercoils 806, 906, 1006, 1106 of the example UAVs 800, 900, 1000, 1110),the example battery 214, the example electronics power controller 320,the example rectifier 322, the example communication system 324, theexample camera 326, the example sensor(s) 1110, the example controller1112, the example motor 1114 and/or, more generally, the example UAVs202, 800, 900, 1000, 1100 of FIGS. 2-5 and 8-11B could be implemented byone or more analog or digital circuit(s), logic circuits, programmableprocessor(s), application specific integrated circuit(s) (ASIC(s)),programmable logic device(s) (PLD(s)) and/or field programmable logicdevice(s) (FPLD(s)). When reading any of the apparatus or system claimsof this patent to cover a purely software and/or firmwareimplementation, at least one of the example motor(s) 210 (which maycorrespond to any of the example motors of the example UAVs 800, 900,1000, 1110), the example receiver coil 212 (which may correspond to anyof the example receiver coils 806, 906, 1006, 1106 of the example UAVs800, 900, 1000, 1110), the example battery 214, the example electronicspower controller 320, the example rectifier 322, the examplecommunication system 324, the example camera 326, the example sensor(s)1110, the example controller 1112 and/or the example motor 1114 is/arehereby expressly defined to include a tangible computer readable storagedevice or storage disk such as a memory, a digital versatile disk (DVD),a compact disk (CD), a Blu-ray disk, etc. storing the software and/orfirmware. Further still, the example UAVs 202, 800, 900, 1000, 1100 ofFIGS. 2-5 and 8-11B may include one or more elements, processes and/ordevices in addition to, or instead of, those illustrated in FIGS. 2-5and 8-11B and/or may include more than one of any or all of theillustrated elements, processes and devices.

A flowchart representative of example machine readable instructions forimplementing the example UAV 1100 of FIGS. 11A and 11B (and, at least inpart, the example UAVS 202, 800, 900, 1000 of FIGS. 3B, 8, 9 and 10) isshown in FIG. 12. In this example, the machine readable instructionscomprise a program for execution by a processor such as the processor1312 shown in the example processor platform 1300 discussed below inconnection with FIG. 13. The program may be embodied in software storedon a tangible computer readable storage medium such as a CD-ROM, afloppy disk, a hard drive, a digital versatile disk (DVD), a Blu-raydisk, or a memory associated with the processor 1312, but the entireprogram and/or parts thereof could alternatively be executed by a deviceother than the processor 1312 and/or embodied in firmware or dedicatedhardware. Further, although the example program is described withreference to the flowchart illustrated in FIG. 12, many other methods ofimplementing the example UAV 1100 of FIGS. 11A and 11B (and, at least inpart, the example UAVS 202, 800, 900, 1000 of FIGS. 3B, 8, 9 and 10) mayalternatively be used. For example, the order of execution of the blocksmay be changed, and/or some of the blocks described may be changed,eliminated, or combined.

As mentioned above, the example process of FIG. 12 may be implementedusing coded instructions (e.g., computer and/or machine readableinstructions) stored on a tangible computer readable storage medium suchas a hard disk drive, a flash memory, a read-only memory (ROM), acompact disk (CD), a digital versatile disk (DVD), a cache, arandom-access memory (RAM) and/or any other storage device or storagedisk in which information is stored for any duration (e.g., for extendedtime periods, permanently, for brief instances, for temporarilybuffering, and/or for caching of the information). As used herein, theterm tangible computer readable storage medium is expressly defined toinclude any type of computer readable storage device and/or storage diskand to exclude propagating signals and to exclude transmission media. Asused herein, “tangible computer readable storage medium” and “tangiblemachine readable storage medium” are used interchangeably. Additionallyor alternatively, the example process of FIG. 12 may be implementedusing coded instructions (e.g., computer and/or machine readableinstructions) stored on a non-transitory computer and/or machinereadable medium such as a hard disk drive, a flash memory, a read-onlymemory, a compact disk, a digital versatile disk, a cache, arandom-access memory and/or any other storage device or storage disk inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, for brief instances, for temporarily buffering,and/or for caching of the information). As used herein, the termnon-transitory computer readable medium is expressly defined to includeany type of computer readable storage device and/or storage disk and toexclude propagating signals and to exclude transmission media. As usedherein, when the phrase “at least” is used as the transition term in apreamble of a claim, it is open-ended in the same manner as the term“comprising” is open ended.

FIG. 12 is a flowchart representing an example method 1200 that may beimplemented by the example UAV 1100 of FIGS. 11A and 11B to wirelesslypower a UAV. The example method 1200 may also be implemented, at leastin part, by any of the example UAVs 202, 800, 900, 1000 of FIGS. 3B, 8,9 and 10. At block 1202, the electronics power controller 320 (FIG. 3B)receives the power from the signal generated in the receiver coil 1106and supplies the power to one or more of the components of the UAV 1100.In some examples, the AC signal induced in the receiver coil 1106 isrectified (via the rectifier 322) to a DC signal. In other examples, oneor more of the components of the UAV 1100 operate via AC and, thus, theelectronics power control 320 regulates the AC power to thecomponent(s). In some examples, power from the receiver coil 1106 isused to charge the battery 214, which is used at a later time to powerone or more of the components of the UAV 1100. The example process maysimilarly be implemented by any of the example UAVs 202, 800, 900, 1000disclosed in connection with FIGS. 3B, 8, 9 and 10.

In some examples, the UAV has a movable receiver coil that may move(e.g., tilt) to capture magnetic fields in different directions. Forexample, in the illustrated example of FIG. 11A, the receiver coil 1106is tiltable via the axle 1108. At block 1204 of FIG. 12, the sensor(s)1110 (FIG. 11A) detect the direction of travel of the UAV 1100. Thesensor(s) 1110 may include accelerometers, gyroscopes and/or otherdevices to detect a direction of travel. At block 1204, the controller1112 (FIG. 11A) determines if the direction of travel has change (e.g.,based on a change measured by one or more of the sensor(s) 1110). Ifthere has been no change in direction, the electronics power controller320 (FIG. 3B) continues to supply power from the receiver coil to theone or more components. If the direction of travel has changed, thecontroller 1112 determines an angle to tilt the receiver coil 1106 basedon the changed direction of travel (block 1206), and the motor 1114activates to rotate the axle 1108 to tilt the receiver coil 1106. Forexample, if spiral transmitter coils (e.g., the transmitter coil 402and/or the spiral transmitter coil 700) are implemented in thehorizontal and vertical sections of a race track, then the direction ofthe magnetic field is in the direction of travel. If the UAV 1100 istraveling through a horizontal track section, the receiver coil 1106 isoriented in the vertical direction to capture the magnetic flux. If theUAV 1100 changes direction and travels through a vertical track section,the motor 1114 rotates the receiver coil 1106 to a horizontalorientation to capture the magnetic flux in the vertical direction. Atblock 1202, the electronics power controller 320 continues to supplypower from the receiver coil 1106 to the one or more components of theUAV 1100.

FIG. 13 is a block diagram of an example processor platform 1300 capableof executing the instructions of FIG. 12 to implement the example UAVs200, 800, 900, 1000, 1100 of FIGS. 2 and 8-11B. The processor platform1300 can be, for example, a server, a personal computer, a mobile device(e.g., a cell phone, a smart phone, a tablet such as an iPad™), apersonal digital assistant (PDA), or any other type of computing device.

The processor platform 1300 of the illustrated example includes aprocessor 1312. The processor 1312 of the illustrated example ishardware. For example, the processor 1312 can be implemented by one ormore integrated circuits, logic circuits, microprocessors or controllersfrom any desired family or manufacturer. In some disclosed examples, theprocessor 1312 may implement the example electronics power controller320 and/or the example processor controller 1112.

The processor 1312 of the illustrated example includes a local memory1313 (e.g., a cache). The processor 1312 of the illustrated example isin communication with a main memory including a volatile memory 1314 anda non-volatile memory 1316 via a bus 1318. The volatile memory 1314 maybe implemented by Synchronous Dynamic Random Access Memory (SDRAM),Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory(RDRAM) and/or any other type of random access memory device. Thenon-volatile memory 1316 may be implemented by flash memory and/or anyother desired type of memory device. Access to the main memory 1314,1316 is controlled by a memory controller.

The processor platform 1300 of the illustrated example also includes aninterface circuit 1320. The interface circuit 1320 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 1322 are connectedto the interface circuit 1320. The input device(s) 1322 permit(s) a userto enter data and commands into the processor 1012. The input device(s)can be implemented by, for example, an audio sensor, a microphone, acamera (still or video), a keyboard, a button, a mouse, a touchscreen, atrack-pad, a trackball, isopoint and/or a voice recognition system. Insome examples disclosed herein, the example input device(s) 1322implement the example sensor(s) 1110 and/or the example camera 326.

One or more output devices 1324 are also connected to the interfacecircuit 1320 of the illustrated example. The output devices 1324 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a printer and/or speakers). The interface circuit 1320 ofthe illustrated example, thus, typically includes a graphics drivercard, a graphics driver chip or a graphics driver processor. In examplesdisclosed herein, the example output devices 1324 implement the exampleelectric motor(s) 210 and/or the motor 1114.

The interface circuit 1320 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) via a network1326 (e.g., an Ethernet connection, a digital subscriber line (DSL), atelephone line, coaxial cable, a cellular telephone system, etc.). Theexample interface circuit 1320 may implement the example communicationsystem 324.

The processor platform 1300 of the illustrated example also includes oneor more mass storage devices 1328 for storing software and/or data.Examples of such mass storage devices 1328 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, RAIDsystems, and digital versatile disk (DVD) drives.

Coded instructions 1332 of FIG. 12 may be stored in the mass storagedevice 1328, in the volatile memory 1314, in the non-volatile memory1316, and/or on a removable tangible computer readable storage mediumsuch as a CD or DVD.

Example methods, apparatus/systems and articles of manufacture towirelessly power a UAV are disclosed herein. Further examples andcombinations thereof include the following:

Example 1 includes an unmanned aerial vehicle including an electricmotor to drive a rotor, a receiver coil to be induced with analternating current when the receiver coil is disposed in an alternatingmagnetic field, and an electronics power controller to supply power tothe electric motor based on the alternating current induced in thereceiver coil.

Example 2 includes the unmanned aerial vehicle of Example 1, wherein theelectronics power controller includes a rectifier to convert thealternating current into a direct current signal, and the direct currentsignal is to power the electric motor.

Example 3 includes the unmanned aerial vehicle of any one of Examples 1or 2, further including a battery, and the direct current signal is tocharge the battery.

Example 4 includes the unmanned aerial vehicle of any one of Examples1-3, wherein the receiver coil is disposed outside of a diameter of therotor.

Example 5 includes the unmanned aerial vehicle of any one of Examples1-4, further including a plurality of rotors, and the receiver coil isdisposed out diameters of the rotors.

Example 6 includes the unmanned aerial vehicle of any one of Examples1-5, further including a camera to record an image of an environment infront of the unmanned aerial vehicle, and the electronics powercontroller is to supply power to the camera based on the alternatingcurrent induced in the receiver coil.

Example 7 includes the unmanned aerial vehicle of Example 6, furtherincluding a communication system to transmit the image to a driver ofthe unmanned aerial vehicle, and the electronics power controller is tosupply power to the communication system based on the alternatingcurrent induced in the receiver coil.

Example 8 includes the unmanned aerial vehicle of any one of Examples1-7, wherein the receiver coil is movable relative to a body of theunmanned aerial vehicle.

Example 9 includes the unmanned aerial vehicle of any one of Examples1-8, wherein the receiver coil is movable from a substantiallyhorizontal orientation to a substantially vertical orientation.

Example 10 includes the unmanned aerial vehicle of any one of Examples1-9, further including an axle coupled to the receiver coil and a motorto rotate the axle to tilt the receiver coil.

Example 11 includes the unmanned aerial vehicle of any one of Examples1-7, wherein the receiver coil includes a plurality of loops facingdifferent directions.

Example 12 includes an apparatus including a transmitter coil defining apassageway through which an unmanned aerial vehicle is to fly and atransmitter circuit to generate an alternating current in thetransmitter coil to create an alternating magnetic field and power theunmanned aerial vehicle.

Example 13 includes the apparatus of Example 12, wherein the transmittercoil is to generate the alternating magnetic field in a directionperpendicular to a central axis of the transmitter coil.

Example 14 includes the apparatus of any one of Examples 12 or 13,wherein the transmitter coil is a birdcage transmitter coil including afirst end ring, a second end ring spaced apart from the first end ring,and a plurality of rungs between the first and second end rings.

Example 15 includes the apparatus of Example 12, wherein the transmittercoil is to generate the alternating magnetic field in a directionparallel to a central axis of the transmitter coil.

Example 16 includes the apparatus of any one of Examples 12 or 15,wherein the transmittal coil is spiral shaped.

Example 17 includes an apparatus including a track section having atransmitter coil to generate an alternating magnetic field and anunmanned aerial vehicle (UAV) having a receiver coil, the alternatingmagnetic field to induce an alternating current in the receiver coilwhen the UAV is disposed in the alternating magnetic field.

Example 18 includes the apparatus of Example 17, wherein the alternatingmagnetic field is generated in a passageway defined by the transmittercoil.

Example 19 includes the apparatus of any one of Examples 17 or 18,wherein the track section is a horizontal track section, and wherein thealternating magnetic field is in a vertical direction.

Example 20 includes the apparatus of any one of Examples 17-19, whereinthe transmitter coil is a birdcage transmitter coil.

Example 21 includes the apparatus of any one of Examples 17 or 18,wherein the track section is a vertical track section, and wherein thealternating magnetic field is in a vertical direction.

Example 22 includes the apparatus of any one of Examples 17, 18 or 21,wherein the transmitter coil is a spiral transmitter coil.

Example 23 includes the apparatus of any one of Examples 17-22, whereinthe receiver coil of the UAV remains substantially horizontal while theUAV flies.

Example 24 includes the apparatus of any one of Examples 17-22, whereinthe receiver coil is tiltable relative to a body of the UAV.

Example 25 includes the apparatus of any one of Examples 17-24, whereinthe track section is a first track section, the transmitter coil is afirst transmitter coil and the alternating magnetic field is a firstalternating magnetic field, further including a second track sectionoperatively coupled to the first track section, and the second tracksection includes a second transmitter coil to generate a secondalternating magnetic field.

Example 26 includes the apparatus of Example 25, wherein the firstalternating magnetic field is in a vertical direction and the secondalternating magnetic field is in a horizontal direction.

From the foregoing, it will be appreciated that the above disclosedmethods, apparatus/systems and articles of manufacture enable wirelesspowering of a UAV via inductive coupling from a transmitter coil, whichmay define a track or track section through which the UAV flies. Inexamples disclosed herein, the power received via inductive couplingenables the UAV to operate (e.g., to operate rotors and/or circuitrywithin the UAV) and/or charge a power storage circuit (e.g., a battery)of the UAV. Operating using power received via the inductive couplingand/or charging a battery of the UAV enables the UAV to travel forfarther distances without having to stop to change and/or recharge abattery of the UAV. As a result, UAV races and/or other activities maybe completed without the need for the stopping during the race and/oractivity to change or recharge a battery of the UAV. Also, byeliminating or reducing the size of the battery, example UAVS arerelatively lighter and more aerodynamic and, thus, can achieve higherspeeds and accelerations than known UAVs.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus/systems and articles of manufacture fairly falling within thescope of the claims of this patent.

What is claimed is:
 1. An unmanned aerial vehicle comprising: a set ofelectric motors; a receiver coil disposed on a same plane as the set ofelectric motors and disposed outside of an area defined between the setof electric motors, the receiver coil having a first diameter that isgreater than a second diameter defined by the area between the set ofelectric motors, the receiver coil to be induced with an alternatingcurrent when the receiver coil is disposed in an alternating magneticfield; and an electronics power controller to supply power to the set ofelectric motors.
 2. The unmanned aerial vehicle of claim 1, furtherincluding a set of rotors, the receiver coil disposed outside a diameterof the set of rotors.
 3. The unmanned aerial vehicle of claim 2, furtherincluding a frame around the set of rotors.
 4. The unmanned aerialvehicle of claim 3, wherein the receiver coil is embedded in the frame.5. The unmanned aerial vehicle of claim 3, wherein the receiver coil iscarried on a top side or bottom side of the frame.
 6. The unmannedaerial vehicle of claim 1, wherein the electronics power controllerincludes a rectifier to convert the alternating current into a directcurrent signal, the direct current signal to power the set of electricmotors.
 7. The unmanned aerial vehicle of claim 6, further including abattery, the direct current signal to charge the battery.
 8. Theunmanned aerial vehicle of claim 1, wherein supply power of the unmannedaerial vehicle is independent of a battery.
 9. The unmanned aerialvehicle of claim 1, further including a camera to record an image of anenvironment in front of the unmanned aerial vehicle, the electronicspower controller to supply power to the camera based on the alternatingcurrent induced in the receiver coil.
 10. An unmanned aerial vehiclecomprising: a body; a receiver coil to be induced with an alternatingcurrent when the receiver coil is disposed in an alternating magneticfield; an axle extending from the body, the receiver coil carried by theaxle, the axle being rotatable to tilt the receiver coil relative to thebody; a motor to rotate the axle to tilt the receiver coil; a sensor todetect a direction of travel of the unmanned aerial vehicle; and acontroller to control the motor to rotate the axle based on thedirection of travel.
 11. The unmanned aerial vehicle of claim 10,wherein the sensor includes at least one of an accelerometer or agyroscope.
 12. An unmanned aerial vehicle comprising: a body; a receivercoil to be induced with an alternating current when the receiver coil isdisposed in an alternating magnetic field; and an axle extending fromand through the body, the receiver coil carried by the axle, the axlebeing rotatable to tilt the receiver coil relative to the body.
 13. Theunmanned aerial vehicle of claim 10, wherein the axle extends across anarea defined by the receiver coil.
 14. The unmanned aerial vehicle ofclaim 10, further including a set of rotors, the receiver coil disposedoutside a diameter of the set of rotors.
 15. The unmanned aerial vehicleof claim 10, further including: a set of electric motors to drive a setof respective rotors; and an electronics power controller to supplypower to the set of electric motors based on the alternating currentinduced in the receiver coil.
 16. The unmanned aerial vehicle of claim15, wherein the electronics power controller includes a rectifier toconvert the alternating current into a direct current signal.
 17. Theunmanned aerial vehicle of claim 16, further including a battery, thedirect current signal to charge the battery.
 18. The unmanned aerialvehicle of claim 15, further including a camera to record an image of anenvironment in front of the unmanned aerial vehicle, the electronicspower controller to supply power to the camera based on the alternatingcurrent induced in the receiver coil.